Starter for engines



Oct. 19 1926. 1,603,650

H. H. TRAIL STARTER FQR ENGINES Filed July 14 1925 I: M //%,y ,1 E

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Herbert Homfio Trail INVENTOR Arromnya.

Patented Oct. 19, 1926.

NlT'ED STATES PATENT -FFlE.

STARTER FOR ENGINES.

Application filed July 14, 1925. Serial No. 43,608..

This invention relates to starter drives for internal combustion engines of the kind comprising a driving shaft on which is mounted a pinion adapted to be moved axially into mesh with a gear on the engine to be started.

The invention has for itsobject to provide improved and simplified means for effecting the axial movement of the pinion into and out of mesh.

The invention broadly consists in providing a pin and cam connection between the driving shaft and the pinion, the cam being shaped so as to move the pinion into mesh with a gradually and progressively increasing velocity. I i

Further features of the invention will be described hereinafter and more particularly pointed out in the appended claims.

Referring now to the accompanying drawings, which illustrate by way of example one convenient form of the invention,

Figure 1 is a side elevation showing the parts in their normal position,

Figure 2 is a sectional elevation showing the parts in operative position,

Figure 3 is a plan view of a detail, and

Figure 4 is a diagrammatic view of the cam-slot.

The driving shaft which is preferably the armature shaft 1 of an electric motor 2, is reduced at its outer end to form a shoulder 3. An annular member 4 is formed with a boss or bearing 5 which is mounted to slide axially on the reduced part of shaft 1, but is prevented from turning on the shaft by a key or spline 6. The forward movement of the member 4 is limited by the shoulder 3 against which the member is normally pressed by a spring 7 which is held in compression by means of a washer 8 and a collar 9 secured on shaft 1 by a screw 10.

A driving pinion 11 is provided with a co-axial sleeve-like projection 12 which loosely fits on the shaft 1 inside the member 4. The member 4: is formed with a cam slot 13 with which enga' es a projection on the sleeve 12, this projectlon being shown as a pin 14 carrying an anti-friction roller 15, the pin being prevented from rotating by means of any suitable retaining device, for example as shown at 16.

The pinion 11 is retained in its normal position shown in Figure 1, by suitable means such as a spring-pressed ball 17 engaging an annular recess 18 in the sleeve 12.

A gear on the engine to be started is shown at 19 and beyond the gear a suitable, cushioning device is provided, such as a ring 20 to which is secured a spring 21, the end convolution of which is snapped into an annular recess in the ring.

The I operation of the drive is as follows When the circuit of the motor 2 is closed the shaft 1 rotates at a high speed, in the direction of the arrow, carrying with it the member 4, but the pinion, by reason of the inertia due to its mass, remainsstationary or rotates at a much lower speed than the shaft. The surface a of the cam slot 13 engages the roller 14 and causes the sleeve 12 to move axially toward the left. This movement of the sleeve 12 pushes the pinion11 into mesh with gear 19 and into engagement with the spring 21. The movement of the pinion continues until the corner'b. of the cam-slot engages the roller 15 as shown in Figure 2, after which a substantially solid drive is obtained, although a degree of flexibility is present by reason of the fact that the member 4 and pinion 11 can reciprocate slightly relatively to each other and the shaft against the action of springs 7 and 21,'as the resistance of the engine varies. As soon as the engine starts to run under its own power at a speed greater than that of the pinion the roller 15 rides along the face a of the cam slot thereby causing the pinion 11 to be drawn to the left out of mesh with gear 19, until the pin 1% lies again in the corner d of the cam-slot as shown in Figure 1. The speed of axial movement of the pinion is not uniform but the cam-slot is so designed that the initial movement of the pinion is relatively slow thereby reducing risk of damage to the teeth. As the pinion enters further into mesh with the' gear the speed of axial movement of the pinion is increased and the force component tending to turn the pinion progressively increases. The action is accomplished in the illustrated example by making the slope of the face a of the camslot very steep, in respect to the axis of the shaft 1, adjacent the corner (Z, and from the corner dthe slope of face a gradually and progressively approaches parallelism with the shaft axistowards the corner 6. The face 0 of the cam-slot is preferably slightly different from face a so, s todemesh the pinion as quickly as possibl For this reason the steep slope of the face 0 adjacent to corner I) is shorter than the steep part of face a adjacent corner d, and consequently the acceleration of the pinion starts earlier during the demeshing movement than during the movement into mesh.

It will be understood that the illustrated embodiment is given by way of modifications falling within the scope of the appended.

claims may be made without departing from the spirit of the invention.

It will be understood that the term pin,

as used in the claims is intended to include any suitable projection or member to coact with the cam.

What I claim is:

1.13m engine-starter drive comprising a driving shaft, a pinion freely mounted for rotary and axial movement on said shaft, and a pin and cam connection between said shaft and pinion, the cam being'so shaped that when the shaft rotates with respect to the pinion the cam coacts with the pin to move the pinion axially at a gradually and progressively increasing velocity until the pinion is in mesh with a gear on the engine to be started and when the pinion overruns the shaft the pin coacts with the cam to produce axial movement of the pinion at a radually and progressively increasing vel ocity until it is withdrawn from mesh with said gear.

aeoaeao 2. An engine starter drive comprising a driving shaft, an annular member rotatable with said shaft, a sleeve freely mounted on said shaft inside said member, a pinion carried by said sleeve and a projection on said sleeve coacting with a cam-slot in said membler, said cam-slot having a shape resembling t at posed at a substantial angle to the axis of said driving shaft.

3. An engine starter drive as claimed in claim 2, wherein the annular member is formed with a bearing which is keyed to a reduced portion of the shaft, a spring being provided to press said member normally against a shoulder at the junction of the shaft with its reduced portion.

4. An engine starter as claimed in claim 2, wherein said projection comprises a pin screwed into said sleeve.

5. An engine starter as claimed in claim 2, wherein said projection comprises a pin screwed into said sleeve, a roller being carried by said pin and adapted to contact with the cam-slot.

6. An engine starter as claimed in claim 2, wherein said projection comprises a pin screwed into said sleeve, and a device being provided to prevent rotation of said pin.

in testimony whereof I afix my signature.

HERBERT HORATIO TRAIL.

of an ellipse with the major axis dis- 

